1. Field of the Invention
The present invention relates to a process for treating semiconductor material with an acid-containing fluid with the formation of water as a product of a chemical reaction.
2. The Prior Art
The provision of suitable base materials from which electronic components can be fabricated, regularly requires process steps during which semiconductor material has to be treated with acid-containing fluids. Such treatments may have various objectives. They are employed, for example, to analyze the crystal structure of the semiconductor material or to uncover imperfections in the crystal. They also serve to detach impurities from the surface of the semiconductor material or to remove layers close to the surface, whose crystal structure has been disturbed due to mechanical action. A further objective of treating semiconductor material with acid-containing fluids is the provision of semiconductor wafers having lateral surfaces which have been etched completely smooth.
Achieving these objectives requires that the acid-containing fluid employed be able to chemically dissolve the semiconductor material in question. As a rule, water is formed, inter alia, during this process as a product of a chemical reaction. The water produced accumulates in the acid-containing fluid and affects the further progress of the treatment of the semiconductor material. Frequently, the rate of removal of material is reduced, so that longer treatment times are incurred or the treatment fluid employed has to be replaced sooner, production costs being raised in either case. An increasing water content in the acid-containing fluid may also have an adverse effect on the result of the treatment of semiconductor wafers. If, for example, the lateral surfaces of silicon wafers are examined which had been treated with a fluid containing hydrofluoric acid and nitric acid, it is found that the residual roughness of the surfaces correlates with the water content in the treatment medium. Where the water content was higher, other conditions being equal, the residual roughness of the lateral surfaces of the silicon wafers is likewise higher.